Do you notice lines on top? They start when slic3r decided to start fans, apparently. Could it be the reason? Too cold? Too hot?
Just commenting on this to see the response.
I’ve had similar issues and I thought it might be related to a loose belt, as the extruder (in my case) moved on the x axis and its position was slightly off. Note: I was also printing a cube. I’ve since tightened the belts, but haven’t printed a tall object where I would notice it.
Voltage drop affecting the steppers when the fans kick in?
@Jonathan_Roeder I don’t think so, I mean it’s impossible current get by fan will alter the right functionality of the all printer, it’s a too much little current, I think
It’s not a cube. The bottom part is larger so it doesn’t start fans…
I have exactly the same problem, and it’s very obvious with white PLA.
I have the same problem with “reprap”, and today I’ve spoken with someone who has said it’s about fans: try to do all print at 100% power fan and then, another one, at 70 or 80% and check the result.